About the Detector 5

Now, analog electric signals from the PMTs are amplified, digitized and then ,sent to the computer with the data acquisition electronics located outside of the spherical tank. The electronics is based on the Analog Transient Waveform Digitizer (ATWD)developed by Lawrence Berkeley National Laboratory (LBNL, California, USA) to meet the requirements of elementary particle experiment, that hold the PMT waveform temporarily as analog data and digitize them via trigger. The ATWD digitizes the each PMT waveform with a sample time of 1.5ns and provides high quality data analysis. Thus, the size of data is so large to such an extent that about 150 GB of data are acquired each day, roughly the same as 250 CD-ROMs . And this size is larger than the one from the Super-Kamiokande experiment, in which nearly 10 times of the PMTs are used, moreover, in comparison with one from the high-energy physics experiment, generally handling large size of data. All data acquired in KamLAND is sent to Tohoku University through the network and backed up to tape each day.

At the end of the story, what is the reason why features of KamLAND have been described by phrases such as “largest in the world” or “number one in the world” until now ? In order to find out the truth nobody in the world has ever seen, it is required that we should experiment using an experimental device with the world’s highest performance. One of the reasons why Japan leads experimental studies in field of neutrino physics is the realization of superior experimental devices. Neutrino physics is rapidly evolving in this moment. Based on excellent ideas and technology, Research Center for Neutrino Science, Tohoku University will promote research for neutrino physics in the future. END